This invention concerns the field of gas lasers and, more particularly, an Argon/Nitrogen laser, or like mixture of noble gas as donor with certain lasing gases at high pressures and high pumping power.
Those skilled in the art are familiar with gas lasers and their characteristics, beginning with the Helium/Neon laser, the first workable gas laser, where Helium was used to absorb RF pumping energy and transfer it to Neon, which, as the lasing gas, would in turn amplify the energy and cause emission of a laser beam.
Workers in the art have for some time been aware of the high electrical conversion efficiencies exhibited by various noble gases such as Xenon, exemplified in the operation of Vacuum Ultra-Violet (VUV) lasers. But, it has hitherto been unsuspected that Argon, or a like noble gas, could be used in a gas laser to develop an output wave length apt for transmission through an atmospheric "window" (a wave length transmitted through atmospheric gases with little or no attenuation). The subject invention has achieved this goal in a novel Argon/Nitrogen laser able to provide an output wave length apt for such transmission. This laser uses electronic excitation energy transfer from Argon to Nitrogen to produce lasing which indicates the feasibility of a new class of high-power noble gas transfer lasers for the visible and shorter wave lengths.
This invention is especially surprising for several reasons. No one has ever before made Argon/Nitrogen mixtures lase in a practical fashion, though some have tried. Apparently, no one ever used Argon (or a like noble donor gas) at a high enough concentration and energy to avoid the well-known "bottle-necking" problem. Indeed, from a theoretical viewpoint, the transfer mechanism and resulting laser action necessary for this did not appear encouraging. Indeed, workers experimenting with Argon/Nitrogen mixtures have asserted they would not lase because energy transfer seemed to favor lower energy levels of the medium -- rather than higher levels as lasing would require. However, systems according to the invention have achieved this startling result, with the equally-surprising result of producing a new 3577A output with some very unique properties and utility.
As more particularly described in the Example and embodiments below, this invention opens the way to a new family of noble-gas donor lasers for producing such results at high pressure. For instance, about seven atmospheres of Argon mixed with only 0.5 atmosphere Nitrogen and exited by a 1.3 MeV electron beam (average current density of 300 amp/cm.sup.2) can produce a very strong laser output (peak power at one-half megawatt or more with reasonable efficiency of about 0.2%). Further, much higher output power and efficiencies (up to a few percent) are indicated. That is, where a conventional low-pressure N.sub.2 laser might exhibit a saturation power of about 2 kw/cc, such an Ar/N.sub.2 laser, according to the invention, can produce a saturation power of about 10 kw/cc. This is believed explained, in part, by a higher rate of collision depopulation of the terminal laser level at higher pressures.